Small bowel transplantation: An overview

Small bowel transplantation (SBT) would, in theory, be the treatment of choice for patients suffering from the short bowel syndrome. Although SBT has been done with a considerable degree of success in some centers [36,145], it is by no means an established or widely applicable therapy for those with short bowel syndrome. The small bowel is unique among vascularized organ grafts because it not only elicits a vigorous rejection reaction but is also capable of inducing graft-versus-host disease (GVHD). Rejection of the graft does not only lead to loss of function but also to bacterial translocation. The risk of fatal sepsis is aggravated by the immunosuppression given to prevent rejection. Here, the history of SBT is described, and recent developments in experimental and clinical SBT, as well as future prospects for this theoretically optimal treatment modality for patients dependent on total parenteral nutrition (TPN) for life, are outlined

From Tetraquark to Hexaquark: A Systematic Study of Heavy Exotics in the Large NcN_c Limit

A systematic study of multiquark exotics with one or $N_c-1$ heavy quarks in the large $N_c$ limit is presented. By binding a chiral soliton to a heavy meson, either a normal $N_c$-quark baryon or an exotic $(N_c+2)$-quark baryon is obtained. By replacing the heavy quark with $N_c-1$ heavy antiquarks, exotic $(2N_c-2)$-quark and $2N_c$-quark mesons are obtained. When $N_c = 3$, they are just the normal triquark baryon $Qqq$, the exotic pentaquark baryon $Q\bar q\bar q\bar q\bar q$, tetraquark di-meson $\bar Q \bar Q qq$ and the hexaquark di-baryon $\bar Q \bar Q \bar q \bar q\ bar q \bar q$ respectively. Their stabilities and decays are also discussed. In particular, it is shown that the ``heavy to heavy'' semileptonic decays are described by the Isgur--Wise form factors of the normal baryons.Comment: 14 pages in REVTeX, no Figure

BasinSim 1.0 A Windows-Based Watershed Modeling Package

BasinSim 1.0 for Windows is the product of a NOAA Coastal Zone Management grant (through the Virginia Coastal Resources Management Program) awarded to Drs. Ting Dai, R. L. Wetzel, I. C. Anderson, and L. W. Haas at the Virginia Institute of Marine Science, College of William and Mary in 1998. Additional support has been provided for the development and testing of this package and production of this user’s guide by grants from Virginia’s Chesapeake Bay Local Assistance Department (CBLAD). BasinSim 1.0 is a desktop simulation system that predicts sediment and nutrient loads for small to mid-sized watersheds. The simulation system is based on the Generalized Watershed Loading Functions (GWLF), a tested watershed model developed by Dr. Douglas Haith and his colleagues at Cornell University, New York (Haith and Shoemaker 1987, Haith et al. 1992). BasinSim 1.0 integrates an easy-to-use graphic Windows interface, extensive databases (land uses, population, soils, water discharge, water quality, climate, point nutrient sources, etc.), and the GWLF model (with modifications) into a single software package. It was designed to enable resource managers to visualize watershed characteristics, retrieve historic data (at the county and sub-watershed levels), manipulate land use patterns, and simulate nutrient (N, P, and organic C) and sediment loadings under various scenarios. The software will assist resource managers in making sound management decisions using the latest technology, information, and scientific knowledge. The system can also be used to educate local organizations and the general public about linkages between basinwide resource management and water quality

Improved lower bounds for the ground-state energy of many-body systems

New lower bounds for the binding energy of a quantum-mechanical system of interacting particles are presented. The new bounds are expressed in terms of two-particle quantities and improve the conventional bounds of the Hall-Post type. They are constructed by considering not only the energy in the two-particle system, but also the structure of the pair wave function. We apply the formal results to various numerical examples, and show that in some cases dramatic improvement over the existing bounds is reached.Comment: 29 pages, 5 figures, to be published in Phys. Rev.

Tumour growth stimulation after partial hepatectomy can be reduced by treatment with tumour necrosis factor α

This study investigated whether partial hepatectomy enhances the growth of experimental liver metastases of colonic carcinoma in rats and whether treatment with recombinant human tumour necrosis factor (TNF) α can reduce this increased growth. Resection of 35 or 70 per cent of the liver was performed in inbred WAG rats, with sham-operated controls (five to eight animals per group). Immediately after surgery 5·105 CC531 colonic tumour cells were injected into the portal vein. After 28 days the animals were killed and the number of liver metastases counted. A 35 per cent hepatectomy induced a significant increase in the median number of liver metastases (28 versus 3 in controls), whereas a 70 per cent resection provoked excessive growth, consistently leading to more than 100 liver metastases and a significantly increased wet liver weight in all animals. TNF-α was given intravenously to rats following 70 per cent hepatectomy or sham operation in a dose of 160 μg/kg three times per week. This had only a marginal effect on tumour development in sham-operated rats but was very effective following partial hepatectomy (median 45 liver metastases). These observations confirm previous findings that surgical metastasectomy may act as a ‘double-edged sword’ by provoking outgrowth of dormant tumour cells and suggest that adjuvant treatment with TNF-α may be of benefit in patients undergoing resection of metastases

Blood transfusions and local tumor recurrence in colorectal cancer. Evidence of a noncausal relationship

OBJECTIVE. The authors analyzed the effect of blood transfusions on the pattern of colorectal cancer recurrence. BACKGROUND. Retrospective studies suggest that blood transfusions are associated with a poor prognosis in patients who undergo operations for colorectal malignancies. In a previously published, randomized trial, it was investigated whether autologous blood transfusions could overcome this putative detrimental effect. However, this did not appear to be the case. METHODS. In the current study, the authors analyzed the patterns of recurrence in 420 patients who underwent curative operations for colorectal cancer. RESULTS. Patients who did not require transfusions (N = 143) had significantly better disease-free survival than those who did need transfusions (N = 277); percentages at 4 years were 73% and 59%, respectively (p = 0.001). No difference was found between both groups in comparing cumulative percentages of patients having metastases; percentages at 4 years were 25% in the group that did not undergo transfusion and 27% in the transfused group. The percentage of cases having local recurrence, however, was significantly increased (p = 0.0006) in the transfused group as compared with the group that did not undergo transfusion; percentages at 4 years were 20% and 3%, respectively. The groups of patients receiving only allogeneic, only autologous, or both types of transfusions all had a significantly higher incidence of local recurrence than the patients who did not receive transfusions, but no differences were found between these three groups. CONCLUSIONS. These findings suggest that the association between blood transfusions and prognosis in colorectal cancer is a result of the circumstances that necessitate transfusions, leading to the development of local recurrences, but not of distant metastases

About the stability of the dodecatoplet

A new investigation is done of the possibility of binding the "dodecatoplet", a system of six top quarks and six top antiquarks, using the Yukawa potential mediated by Higgs exchange. A simple variational method gives a upper bound close to that recently estimated in a mean-field calculation. It is supplemented by a lower bound provided by identities among the Hamiltonians describing the system and its subsystems.Comment: 5 pages, two figures merged, refs. added, typos correcte